Cloud services are increasingly gaining importance and applicability in numerous application domains such as storage, computing services, collaboration platforms, etc. Clouds offer a huge economic benefit to companies, private individuals, and public organizations that deploy or provision cloud services in a cost effective manner. However cloud storage and computation services introduce new threads to data security. Customers of cloud services lose control over their data and how data is processed or stored. This makes users reluctant to use cloud services.
To address this problem, i.e. to enable users to verify the integrity and availability of their outsourced data, so-called proofs of retrievability as disclosed in the non patent literature (NAOR, M., AND ROTHBLUM, G. N. The Complexity of Online Memory Checking. In FOCS (2005), pp. 573-584), have been proposed. These proofs of retrievability (POR) provide end clients with the assurance that the data is still available and can be entirely downloaded if needed.
Conventional methods share a similar system and attacker model including a cloud user and a rational cloud provider. Here a “malicious” cloud aims at minimizing costs, for example by not deploying appropriate security measures in their datacenters or by intentionally modifying or for example deleting user data. The guarantees provided by the conventional methods and systems therefore largely depend on the users themselves who are required to regularly perform verification in order to react as early as possible in the event of data loss. Furthermore, said verification requires the user to be equipped with devices that have network access and that can tolerate computational overhead incurred by the verification process.
As a result, users must either accept this burden and regularly verify their outsourced data or entrust cloud providers to deploy necessary security mechanisms to ensure data integrity in spite of server failures exploits, etc. However, the latter option has the disadvantage of transferring costs to the cloud service providers.